In view of today's efforts to preserve myocardial function in acute myocardial infarction, the prevalence and extent of persistent right ventricular dysfunction was analysed in a prospective study of 127 patients admitted with a first myocardial infarction without thrombolysis. Right ventricular ejection fraction measured at hospital discharge by radionuclide angiocardiography was related to the location of infarction as judged electrocardiographically, its size as estimated enzymatically, and by the simultaneously measured left ventricular ejection fraction. Two opposite patterns of right and left ventricular function were observed in relation to the location of infarction: the right ventricular ejection fraction was significantly depressed in inferior, but not in anterior, infarction and the reverse was true for left ventricular ejection fraction (P less than 0.001 between infarct locations for both right ventricular ejection fraction and left ventricular ejection fraction). There were significant correlations between peak levels of creatine kinase and left ventricular ejection fraction for anterior (r = 0.76, P less than 0.001) and inferior (r = 0.57, P less than 0.001) infarction, while peak levels of creatine kinase and right ventricular ejection fraction correlated only in inferior infarction (r = 0.45, P less than 0.01). There was no overall correlation for left ventricular ejection fraction and right ventricular ejection fraction (r = 0.28, P NS), despite the fact that right ventricular ejection fraction was lower in patients with severely reduced left ventricular ejection fraction than in those with normal left ventricular function (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)